I keep my photos because they can memorise the moment.
But in order to memorise anything they would need consciousness, which is of course impossible. A photograph does not have a brain:
Only humans can memorise things, so perhaps you mean:
Be careful with ‘memorise‘. We don’t usually memorise ‘moments’. We generally memorise information, and this often requires continued and intensive concentration. For example if you want to remember somebody’s phone number, you must first of all memorise it. The memory of the number then stays in your head ready for the next time you need it. With a photograph, the memory might not stay in your head. Rather, you remember the moment whenever you look at the photograph. In this sense the photo acts as ‘a reminder‘.
Indonesians would do well to read through the previous paragraph and consider the translations of ingat and its forms, and also hafal and its forms.